1) Field of the Invention
The present invention relates to a loop status monitoring apparatus, and more particularly, to a loop status monitoring apparatus that can identify a device with a connection failure occurred when no signal failure is found even if an initialization process in an arbitration loop is stopped to quickly restore the loop to a normal status.
2) Description of the Related Art
Conventionally, loop status monitoring devices that monitor the status of a plurality of devices and arbitration loops that have switches for control the connection between the devices. When a connection failure occurs in the arbitration loop, the conventional loop status monitoring device has to await completion of the initialization process of the arbitration loop in order to identify the device that has caused the connection failure. When the initializing process is stopped, the arbitration loop cannot be used and the device cannot be accessed. Even if connection failure is found because of a signal failure during the initialization process, countermeasure in the form of switching to reserve arbitration loop is necessary since the device causing the connection failure is not identified. Even if a reserve arbitration loop is used, if the device with the connection failure is not segregated, there is a possibility of connection failure occurring in the reserve arbitration loop as well.
Recent technological developments have produced devices which automatically send unvarying signals even if failure occurs. In this case, even if the initialization process in the arbitration loop halts, because no signal failure is found the device with the connection failure cannot be identified, and quick restoration of the loop to normal status cannot be achieved. For instance, in the conventional technology disclosed in Patent literature 1, a process is proposed whereby, if intermittent connection failure occurs in the arbitration loop to which a disk is connected, normal disk process is temporarily stopped to perform a loop diagnostic process for identifying the failed part, and a reserve loop is pressed into server to perform the normal disk process. However, in the conventional technology disclosed in Patent literature 1, even if the initialization process in the arbitration loop halts, because no signal failure is found the device with the connection failure cannot be identified, and quick restoration of the loop to normal status cannot be achieved.